In the field of radiation therapy for low-lying bowel cancers, there are several methods that historically have been utilized to irradiate the distal gastrointestinal tract. One method includes an external beam. Other methods are essentially internal, such as brachytherapy, which are often difficult and cumbersome in actual practice.
In general, radiotherapy, as applied to the distal gastrointestinal tract, is used in preoperative, postoperative, definitive and palliative modes.
In the preoperative mode, radiotherapy can reduce the extent of the cancer so as to facilitate surgical resections.
In the postoperative mode, radiotherapy is utilized after surgical resection when pathologic findings warrant the use of radiotherapy.
In the definitive mode, radiation therapy is used widely in connection with anal cancers, unresectable rectal cancers, and resectable recto-sigmoid cancers which occur in patients who are medically not suited for surgery or who refuse surgery.
Palliative uses of radiation therapy include addressing such quality of life issues as stoppage of bleeding, etc.
Known problems which are encountered with the use of external radiation therapy include the toxicity caused by bowel irradiation and the relative long duration over which treatment must be administered in order to achieve reasonable benefits versus risks.
With respect to internal radiation therapy, problems often arise relating to the difficulty of implementing the treatment and the lack of a cohesive procedure for incorporation into an overall health management program.
In addition, organ preservation is sometimes hindered by the lack of the convenient availability of radiation therapy facilities or the significant time commitment needed to implement the radiotherapy program. This problem was especially apparent in connection with breast cancer in terms of breast conservation treatment.